Researcher usually loads single tissue slide into microscope stage, adjusts objective visual field and focal length for image scanning when he/she intends to scan the single tissue slide. If the single tissue slide has multiple regions require to be scanned separately, the researcher needs to adjust the objective visual field for capturing the different region image respectively, and he/she needs to adjust objective visual field and focal length again when another tissue slide is loaded. Therefore, improve scanning speed is difficult because the researcher has to adjust objective visual field and focal length again and again.